Monday, July 30, 2012

Arithmetic Rack or Rekenrek as noted by Math Coach!

I explored the Rekenrek or arithmetic rack when I read about it on Math Coach's Blog. I was impressed with the research I did on it this weekend.  After all, with Common Core we will dig
deeper allowing students to develop powerful understandings of numbers, the meaning of those
numbers, their relationship to one another, and of course how to operate with them. I noted from
my readings that counters, number lines, base-10 blocks and other manipulative items are limited, as a means of cultivating number sense, or to fostering a student's understanding of both addition and subtraction.

It was stated that the Rekenrek or arithmetic rack has emerged as perhaps the most powerful of all
models for young learners. This tool combines the features of the number line, counters, and base-10 models, and I think we can make them easily.  Math Coach had a model on her blog.  I thought about
the dry erase boards from Dollar Tree which are not really that big. I considered using those putting the beads on elastic that could slide on and off easily. Like killing two birds with one stone.  I haven't tried it yet, but I will check it out. I did find the racks online and some were as cheap as $ 5.00 and perhaps, when I get my school allocations I might purchase enough for my small group teaching.

I created the one above in my Smart Notebook and my students will be capable of manipulating it since I teach them how to group objects. They suggested one move to create a number instead of single sliding of  beads. It was suggested that the model could be adapted to accommodate varied levels of students.  Kinders will only need one string to 5. It was stated that the Rekenrek combines features of the number line, counters and base-10 models which makes it highly effective.

The strategy focuses on the highlighting of groups of 5 which offers a visual for early learners as they enter the beginning stages of understanding that one number may be a combination of two or more other numbers. As I created the model above, the student will visually see the number 8 as two distinct parts or one group of 5 and three more.  On the other hand a student that is more advanced may see the number 15 as a group of 10 and 5 more.

It was noted that using the Rekenrek which focuses on 5 and 10 is instrumental in helping children visualize numbers, seeing them as collections of objects in groups.  "This strategy of seeing numbers "inside" other numbers - particularly 5 and 10 - is a precursor to the development of informal strategies for addition and subtraction that students will naturally acquire through repeated use of the Rekenrek." Basically it helps students see numbers as groups of 5 or 10, "doubles" and so on instead of counting every object in a set.

For example, think of subitizing as the ability of the student to instantly recognizance quantities up to 10 without depending on the routine counting.  Using this in an example with the model above, 8 is subitized, and seen as two groups-one group of 5, and one group of 3.  I will share more as I read on and explore more complex decomposition of numbers. This information was taken from my reading of Rekenrek by Dr. Jeffrey Frykholm.  I find this read exciting and plan on using it with my 2nd grade math students. Well off to relax after a long day in my classroom with a few more to come before I am ready to roll!


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